The common set of jumper cables comprises two cables with clamp-like devices electrically connected to each end of each cable. In use, the clamp-like devices of one cable are attached to the positive terminal or pole of a charged batter (source point), and the clamp-like device of the same cable is attached to the positive pole or terminal of a discharged battery (delivery point). In a similar manner, one clamp-like device attached to one end of the second cable is attached to the negative pole or terminal of the charged battery, and a clamp-like device attached to the opposite end of the second cable is attached to the negative pole of the discharged or dead battery. Electrical energy flows from the charged point to the discharged point.
The common, available sets of jumper cables are designed for use with automobiles and light trucks and vehicles or systems with related power demands. The capacity of the jumper cable systems, cables and clamp-like devices is 6 to 12 volts at generally less than 1,000 amps.
The electrical circuitry is simple. Electrical current is carried from the charged battery, “through” the discharged (dead) battery to for example, a starter motor for an engine. The electrical energy is carried through a pair of cables connected appropriately to the charged battery and to the discharged battery, although as one skilled in the art recognizes, the connection could be directly to the starter motor or other device.
Jumper cable systems are subject to losses in efficiency as a result of design and laws of physics. By way of illustration, consider only one of the two cables comprising the common jumper cable system. Electrical current travels from the terminal of the charged battery to the clamp-like device attached to that terminal and then passes across the clamp-like device to the cable to be transmitted to the clamp-like device at the opposite end of the cable, thence across that clamp-like device to be discharged to the terminal at the point of demand. In effectively all situations, source voltage is fixed and determined by the charged battery. Thus, electrical powered delivered is a function of amps delivered. In a perfect situation, all current delivered by the charged battery to the clamp-like device connecting the jumper cable system to the charged battery would be transmitted to the demand point for use. This is not practically possible.
Electrical current passing through a conductor encounters resistance which ultimately leads to the generation of heat. Obviously, electrical energy used to generate the heat is lost and will not be delivered to the demand point for use. Furthermore, heating increases resistance that in turn further increases heating and energy loss to the demand point. Heating, hence energy loss is a complex function of the duration and rate of the current flow, the amperage, and the resistance of the conductors through which the current is flowing.
Although the delivery cables may be selected to minimize heating and resultant energy loss, existing clamp-like devices represent a significant source of inefficiency as a result of heating. The basic design of the clamp-like device is a pair of jaws. The cable is connected to one member of the pair, but the entire clamp-like device is energized as a result of physical contact between the jaws by means of a pivot point and spring, and as a result of the contact of both members of the pair of jaws with the terminal of either the charged battery or of the discharge battery. Note the inefficiency occurs with clamp-like devices at both the charged and discharged terminals. Frequently for purposes of combinations of strength, weight, costs, and similar devices factors, the conductivity of the clamp-like device is less than the conductivity of the transmission cable to which clamp-like devices are attached. When a jumper cable system is used for relatively brief periods, less than several minutes at moderate current loads of 6 to 12 volts delivered at less than 250 amps, heating and losses of efficiency related to available systems is relatively inconsequential; however, with longer durations and higher amperage loads reflected by higher amperage of current delivered delivered, for example 1800 to 3,800 amps, heating and the associated inefficiencies represent a significant problem.
U.S. Pat. No. 4,153,321 issued May 8, 1979 to Pombrol recognizes the need for a secure contact between the jaws connected to the battery post or terminal and a booster cable. The contact areas of each arm of the connector clamp are brought together and secured by a ratchet-like action between teeth of a flexible member of the connector clamp.
Safety of use is the focal point of U.S. Pat. No. 4,662,696 issued May 5, 1987 to Asbury. Sparks resulting from connecting the jaw-like clamps of jumper cables to battery terminals have triggered battery explosions resulting in significant injuries. The '696 patent claims a switch in the second cable that is open when the cable ends are connected to the battery terminals and closed after the potentially dangerous connection is completed to complete the circuit and allow current to flow. The switch is a spark retarding device positioned in an insulated housing to minimize the occurrence of spark induced battery explosions.
U.S. Pat. No. 4,721,479 issued Jan. 26, 1988 to Shuman claims alternative methods to reduce explosion hazards when jumper cables are connected to batteries. Either only one or both cables of a jumper cable system are severed near their midpoint. If only one cable is severed, the cable is reconnected by an allegator clamp fixed to one severed end gripping the conductor portion of the other severed end, after the cable has been attached to the battery terminals. If both cables are severed, a jack-type plug is used to connect one cable, and the previously described jaw connector is used to join the severed ends of the other cable.
Modifications to the jaw-clamps of a booster cable system are claimed in U.S. Pat. No. 4,862,457 issued May 2, 1989 to Varatta. In the '457 patent, the jaw portion of the cable attachment clamp is positioned at an angle to the handle portion of the clamp to facilitate attachment of the clamp to a battery terminal located on the side, rather than on the accessible top surface of the battery. The improved clamp is also adapted for use on top mounted battery terminals.
Other, less technical considerations have not been ignored in booster cable technology. U.S. Pat. No. 5,316,498 issued May 31, 1994 to Hooper claims a system to securely store a set of booster cables or booster cable system to minimize damage to the system.
Recent years have witnessed a dramatic increase in the number of diesel-powered automobiles, as well as pickup trucks used as personal vehicles, and a profusion of sport utility vehicles. Otherwise, the use of diesel engines in commercial vehicles and for heavy construction and farm equipment remains at least constant.
Batteries serving diesel powered machinery of all types are subject to failure for the same reason they fail in gasoline powered applications. Thus, diesel powered equipment will find use for jumper cable systems just as gasoline systems do. Compared with the batteries commonly used in electrical systems of gasoline powered automobiles and equipment in general, batteries used for electrical systems in diesel equipment, starter motors for an excellent example, require more energy. Jumper cable systems supplying current for diesel electrical systems must be capable of delivering more current, potentially over longer intervals of time periods.
Although the basic jumper cable system has not changed, various improvements have been made. However, current technology does not address the loss of electrical power and the need for more efficient jumper cable systems. Thus there remains room and need for high efficiency, heavy duty jumper cables that can be used with safety and convenience to supply temporary power to electrical systems associated with diesel powered vehicles and equipment and that simultaneously can be used to supply electrical systems common to gasoline powered vehicles and equipment.